Evidence of ventilatory constraints during exercise in hypermobile Ehlers–Danlos syndrome

Purpose Hypermobile Ehlers–Danlos syndrome (hEDS) is a connective tissue disorder with many different symptoms such as pain, fatigue, dysautonomia, or respiratory symptoms. Among the respiratory manifestations described, the most frequent are exertional dyspnea and breathing difficulties. Mechanical ventilatory constraints during exercise could participate in these respiratory manifestations. The objective of this study was to explore the response of pulmonary flow-volume loops to exercise in patients with hEDS and to look for dynamic hyperinflation and expiratory flow limitation during exercise. Methods For this purpose, breathing pattern and tidal exercise flow-volume loops were recorded at two workloads (30% and 80% of the peak power output) of a constant load exercise test. Results Twelve patients were included (11 women, mean age 41 ± 14 years). The results showed a decrease ( p = 0.028) in the inspiratory capacity (from 3.12 ± 0.49 L to 2.97 ± 0.52 L), an increase ( p = 0.025) in the end-expiratory lung volume (from 0.73 ± 0.68 L to 0.88 ± 0.66 L, i.e., from EELV comprising 17 ± 12% to 21 ± 12% of forced vital capacity) between the two workloads in favor of dynamic hyperinflation, and half of the patients had expiratory flow limitations. Conclusion This exploratory study provides evidence for mechanical ventilatory constraints during exercise in patients with hEDS, which may induce discomfort during exercise and could contribute to the respiratory symptomatology. Trial registration number This study is part of a larger clinical trial (ID: NCT04680793, December 2020).